The present invention relates to a washer to be used in a fastener, and in a method of fastening.
It is known to fasten objects with one another with a fastener which has a multi-part replacement nut, for example including an inner sleeve, an outer sleeve, and a washer. Such a replacement nut is disclosed for example in our U.S. Pat. No. 5,341,560. Another replacement nut is disclosed in our U.S. Pat. No. 6,254,323 in which a bolt has a spline underneath its upper thread, to which a washer is non-rotatably connected, and the bolt also has engaging means for applying a reaction force, while an active force of the same tool turns the nut on the bolt thread and the washer face. In the fastener disclosed in both above mentioned patents, the common features are the use of the action and reaction force of one tool, the elimination of reaction arms on torque powertools, the conversion of torque to torsion-free bolt stretching and obtaining for the first time the desired residual bolt load as compared to torque, which is estimated based on calculated frictions rather than actual frictions or hydraulic tension, which is based on estimated bolt relaxation when the force is transmitted from the elongated bolt to the hand-tight nut.
The problem found in the industry with the fastener disclosed in U.S. Pat. No. 5,341,560 is that, since the nut has to be made with two sleeves whose outside diameter has to meet the outside diameter of a regular nut, both sleeves have less material than a regular nut. This requires the use of high strength materials, which causes a reluctance on the part of the customers to change materials and fear of the unknown. In the fastener disclosed in U.S. Pat. No. 6,254,323 the bolt needs to be altered, which is not just costly but not easily acceptable by the industry. In other words the fastener disclosed in our U.S. Pat. No. 5,341,560 requires alteration of the nut, while the fastener disclosed in our U.S. Pat. No. 6,254,323 requires alteration of the bolt. In addition, both versions are expensive to produce, adding to customer's reluctance to purchase these fasteners.